Feeds and Feedstuffs 1

Lecture 11

What are the five major nutrient categories?

water

energy

protein

vitamins

minerals

What are the primary sources of water?

drinking water, feed moisture

What are the primary sources of energy?

carbohydrates, lipids/fats, protein

What are the primary sources of protein?

dietary amino acids, microbial protein

What are the primary sources of vitamins?

feed ingredients

What are the primary sources of minerals?

soil and feed sources

What are the major functions of water?

thermoregulation, metabolism

What are the major functions of energy?

maintenance, growth, production, reproduction

What are the major functions of protein?

tissue synthesis

What are the major functions of vitamins?

metabolic cofactors

What are the major functions of minerals?

structural and metabolic roles

Energy is commonly expressed as what values?

Kcal

Mcal (feeds)

Total Digestible Nutrients (TDN)

In ruminants, what is the dietary protein used by rumen microbes and transformed into microbial protein?

degradable intake protein

In ruminants, what is the dietary protein that remains undegraded through the rumen, and will be available for digestion and absorption in the small intestine?

undegradable intake protein (aka bypass protein)

In ruminants, which type of protein is important to help meet protein needs of high producing dairy cattle?

undegradable intake protein (aka bypass protein)

What are the major components measured in feedstuffs?

dry matter (DM)

ash (minerals)

crude protein

fiber

non structural carbohydrates

Feedstuffs/ingredients should only be compared on what basis?

dry matter basis

Why should feedstuffs/ingredients only be compared on a dry matter basis?

because feeds vary widely in moisture content and animals need to meet dry matter intake needs

Cell contents of plants include what?

sugars (glucose)

starch

proteins

The cell wall in plants contains what?

cellulose

hemicellulose

lignin

Which component of the cell in plants provides structural fiber?

cell wall

Which component of the cell in plants is highly digestible?

cell contents

What refers primarily to plant cell wall components that resist digestion by mammalian enzymes?

fiber

What are the three major fiber components?

cellulose

hemicellulose

lignin

Which major fiber component is most digestible: cellulose, hemicellulose, lignin?

hemicellulose

Which major fiber component is indigestible: cellulose, hemicellulose, lignin?

lignin

Ruminants rely on what to digest?

microbial fermentation

What methods of measuring fiber are the focus of modern forage evaluation?

NDF and ADF

Which method of measuring fiber predicts intake by measuring hemicellulose, cellulose, and lignin?

NDF

Which method of measuring fiber predicts digestibility by measuring cellulose and lignin?

ADF

Which value represents total cell wall content?

NDF

A higher NDF, means a lower or higher intake?

lower

What is considered an excellent NDF value?

<40%

What is considered a poor NDF value?

>65%

A higher ADF means higher or lower digestibility?

lower

What is considered a good ADF value?

30-35%

What is considered a poor ADF value?

>45%

As lignin increases, the digestibility of cellulose ____.

decreases

Why does the solubility of cellulose decrease as lignin increases?

lignin interferes with microbes reaching cellulose

What happens to NDF and ADF as a pasture grass matures?

both increase

What is a very important component in horse nutrition that can be digested by endogenous enzymes like amylase and may be quite high in certain hays, and usually quite high in grains?

non-structural carbohydrates (NSC)

Why are non-structural carbohydrates (NSC) so important in horse nutrition?

laminitis

colic

What happens as a forage plant matures and why?

fiber increases

protein decreases

energy decreases

digestibility decreases

—> occurs due to lignification of cell walls

True or false: Harvest timing strongly affects forage quality.

True

Forages are generally divided into what three categories?

grasses

legumes

forbs (bushes, small trees)

Give examples of grasses.

bermuda grass

ryegrass

timothy —> common in horse pastures

orchardgrass —> common in horse pastures

tall fescue

smooth bromegrass

How do legumes differ from grasses?

fix nitrogen in soil

contain higher protein

contain higher calcium

Give examples of legumes.

alfalfa

clovers

soybeans

What forage type is often used to improve pasture nutritional value?

legumes

Which type of fescure produces toxic ergot alkaloids that cause animal disorders and has an endophyte that confers drought resistance?

TE fescue (TE = toxic endophyte)

TE fescue contains the endophyte named what?

Acremonium coenophialum

What problems are caused by ergot alkaloids produced by TE fescue?

Cattle: fescue foot (gangrene), summer fescue toxicosis

Horses (mares): prolonged gestation, weak foals, abortion, agalactia

What is the major issue with Bermuda grass becoming very fibrous when over mature?

risk of impactions

What is the term for undergound stems of bermuda grass?

rhizomes

What is the term for above ground stems of bermuda grass?

stolons

What condition results from a fungal endophyte produced in the seed head of perennial ryegrass and results in issues flexing legs and walking, convulsions, and death?

ryegrass staggers

What condition results from a saprophytic fungus growing on dead perennial ryegrass producing sporidesmins and causes photosensitivity reaction and skin lesions?

facial eczema

What conditions may be caused by perennial ryegrass ingestion?

ryegrass staggers

facial eczema

What condition may be caused by annual ryegrass ingestion?

annual ryegrass toxicosis

What condition can result from annual ryegrass containing corynetoxin and causes high stepping gaits, incoordination, convulsions, brain damage, and death?

annual ryegrass toxicosis

What are the two problems associated with alfalfa?

bloat in cattle if grazed

blister beetle toxicity in horses

Why is alfalfa associated with blister beetle toxicosis in horses?

the beetles are baled with the hay and contain cantharidin

What forage may cause prolonged gestation and/or agalactia in mares?

TE fescue

How does sweet clover interfere with blood clotting?

sweet clover is high in coumarin which is converted by molds to dicoumarol —> dicoumarol is anti-vitamin K and interferes with blood clotting

What is caused by red clover with rust colored mold producing slaframine?

red clover slobbers (excessive slobbering in horses)

Acute (short term) Alsike clover poisoning causes what in horses?

photosensitization

Chronic (long term) Alsike clover poisoning causes what in horses?

liver failure accompanied by neurological impairment

White clover contains cyanogenic glycosides that can produce HCN released during chewing, which can cause what?

detoxification of HCN in rumen and liver produces thiocyanate, which can inhibit binding of iodine in thyroid gland